Chmod Calculator

chmod (change mode) is a Linux/Unix command that changes the access permissions of files and directories. It uses numeric (like 755) or symbolic (like rwxr-xr-x) notation.

chmod 755 means the owner has read, write, and execute permissions (7=rwx), while group and others have read and execute permissions (5=r-x). This is commonly used for executable files and directories.

chmod 644 gives the owner read and write (6=rw-), group and others read-only (4=r--). chmod 755 gives the owner full access (7=rwx), group and others read and execute (5=r-x). Use 644 for files and 755 for directories/executables.

Setuid (4000) runs a program as the file owner. Setgid (2000) runs as the file group or keeps group ownership in directories. Sticky bit (1000) prevents users from deleting others' files in shared directories like /tmp.